add stripped-down & slightly-modified version of LibTomCrypt SHA512

src/sha512.h

@@ -0,0 +1,34 @@
+/* public api for Thomas Pornin's BearSSL SHA-512 implementation */
+
+/** @file
+ *  SHA-512 hash API.
+ */
+
+#ifndef __LIBSTROPHE_SHA512_H__
+#define __LIBSTROPHE_SHA512_H__
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* make sure the stdint.h types are available */
+#include "ostypes.h"
+
+typedef struct {
+    uint64_t length, state[8];
+    uint8_t curlen;
+    uint8_t buf[128];
+} sha512_context;
+
+#define SHA512_DIGEST_SIZE 64
+
+void sha512_init(sha512_context *cc);
+void sha512_process(sha512_context *cc, const uint8_t *data, size_t len);
+void sha512_done(sha512_context *cc, uint8_t *dst);
+
+void sha512_hash(const uint8_t *data, size_t len, uint8_t *digest);
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __LIBSTROPHE_SHA512_H__ */